Plain English Summary
Background and study aims
This study is performed in patients having cardiac (heart) surgery with the use of a heart-and-lung machine. Blood supply to the brain is normally regulated by a mechanism called 'cerebral autoregulation'. Cerebral autoregulation means that the body preserves blood supply to the brain despite wide variations in blood pressure. A way of assessing blood supply to the brain is measuring the oxygen content of a small part of the brain tissue using near-infrared spectroscopy. This is a non-invasive method where two adhesive pads are placed on the patient's forehead. These pads send out light at a frequency close to the infrared part of the electromagnetic spectrum. This light can penetrate the skull and is reflected by the brain tissue. By analysing the reflected light, the oxygen saturation (i.e. the amount of oxygen present) of a small portion of the brain can be measured. Recent studies investigated the effects of different blood-pressure-increasing medications on the cerebral oxygenation (oxygen levels in the brain) and found that after a dose of the drug phenylephrine, blood pressure was raised, but cerebral oxygenation decreased. A possible mechanism for this could be that phenylephrine slightly increases the resistance of blood vessels to the brain and thus decreasing the blood flow; this potentially leads to a decrease in the oxygenation of brain tissue. In this study we want to investigate this hypothesis further by performing several blood-pressure-increasing manoeuvres in patients connected to a heart-and-lung machine during cardiac surgery. These include administration of two different substances widely used in standard care of anaesthesia to raise blood pressure (phenylephrine and vasopressin) and a increment (increase) in the heart-and-lung machine pump flow (to simulate a rise in cardiac output). These different manoeuvres will all raise blood pressure, but might have different effects on cerebral oxygenation. The results of this study will help to get a better understanding of physiological (normal) mechanisms that control blood supply to the brain.
Who can participate?
Adults aged 18-70 having cardiac surgery requiring a heart-and-lung machine.
What does the study involve?
During surgery, the blood pressure of all the participants are raised in three different ways in a randomized order. The first method of raising blood pressure is α1-mediated, with phenylephrine, while CPB (cardiopulmonary bypass)-flow is clamped. The second method is non-α1-mediated, with vasopressin while CPB-flow remains unchanged. The third method involve increasing CPB-flow. Cerebral oxygenation and arterial blood pressure is measured for each participant before and after each method is applied.
What are the possible benefits and risks of participating?
Not provided at time of registration.
Where is the study run from?
Academic Medical Center AMC (Netherlands)
When is the study starting and how long is it expected to run for?
January 2010 to June 2013
Who is funding the study?
Academic Medical Center, AMC Amsterdam (Netherlands)
Who is the main contact?
Mr Niek Sperna Weiland
Trial website
Contact information
Type
Scientific
Primary contact
Mr Niek Sperna Weiland
ORCID ID
http://orcid.org/0000-0003-1305-1846
Contact details
Academic Medical Center
Department of Anesthesiology
Meibergdreef 9
Amsterdam Zuidoost
1105 AZ
Netherlands
Additional identifiers
EudraCT number
ClinicalTrials.gov number
Protocol/serial number
Protocol revision 2.3; nov 23, 2009. NL29879.018.09. MEC 09/280.
Study information
Scientific title
Cerebral oxygenation during changes in vascular resistance and flow in patients on cardiopulmonary bypass: a randomized cross over trial
Acronym
Study hypothesis
Phenylphrine causes α1-receptor mediated cerebral vasoconstriction
Ethics approval
Medisch Ethische Toetsingscommissie Academisch Medisch Centrum, ref: 09/280
Study design
Single center interventional study
Primary study design
Interventional
Secondary study design
Randomised cross over trial
Trial setting
Hospitals
Trial type
Other
Patient information sheet
Participant information available in Dutch only. Not available in web format, please use the contact details below to request a copy of the patient information sheet.
Condition
Physiology of brain perfusion.
Intervention
During the cardiopulmonary bypass-phase of cardiac operations, when the patients were hemodynamically stable and a CPB-flow was 2.6 L•m-2•min-1 subjects underwent three interventions in randomized order. During these interventions no other hemodynamic interventions were performed.
1. Mean arterial blood pressure (MABP) was raised by increasing CPB-flow by 0.5 L•m-2•min-1 for five minutes
2. MABP was raised ≈15 mmHg by an α1-mediated increase in SVR with a PE bolus of 50-150 µg while CPB flow remained unaltered at 2.6 L•m-2•min-1
3. MABP was increased ≈15 mmHg by a V1-receptor mediated increase in SVR with a VP bolus of 0.1 - 0.4 IU while CPB flow remained unaltered at 2.6 L•m-2•min-1
Intervention type
Mixed
Phase
Drug names
Primary outcome measure
Cerebral oxygenation before and after each intervention.
Secondary outcome measures
Arterial blood pressure before and after each intervention.
Overall trial start date
01/01/2010
Overall trial end date
14/06/2013
Reason abandoned (if study stopped)
Eligibility
Participant inclusion criteria
1. Age 18-70 years
2. Patients scheduled for elective cardiac surgery (CABG, aortic valve repair, mitral valve repair or combinations of the former), using mil hypothermic cardiopulmonary bypass.
3. Written informed consent present
Participant type
Patient
Age group
Adult
Gender
Both
Target number of participants
10
Participant exclusion criteria
1. Age ≤18 years
2. Emergency operations
3. Brain pathology in history (CVA)
4. Severe carotid artery stenosis (if no data is available, an echo-Doppler will be performed by the anesthesiologist after induction of anesthesia, prior to surgery)
5. Severe COPD
6. Absent informed consent
7. SaO2<90% at room temperature
8. Diabetes
9. Kidney failure
Recruitment start date
23/03/2010
Recruitment end date
14/06/2013
Locations
Countries of recruitment
Netherlands
Trial participating centre
Academic Medical Center AMC
Meibergdreef 9
Amsterdam-Zuidoost
1105 AZ
Netherlands
Sponsor information
Organisation
Academic Medical Center AMC
Sponsor details
Meibergdreef 9
Amsterdam Zuidoost
1105AZ
Netherlands
Sponsor type
Hospital/treatment centre
Website
Funders
Funder type
Hospital/treatment centre
Funder name
Academic Medical Center, AMC Amsterdam (Netherlands)
Alternative name(s)
Funding Body Type
Funding Body Subtype
Location
Results and Publications
Publication and dissemination plan
Intention to publish date
31/12/2015
Participant level data
Stored in repository
Basic results (scientific)
Publication list